FIX: A2029 Incorrectly Generated If Operand = [ebx][ebx]

 Last reviewed: September 16, 1997
Article ID: Q79067
6.00 | 6.00 MS-DOS | OS/2 kbtool kbfixlist kbbuglist

The information in this article applies to:

  • Microsoft Macro Assembler for MS-DOS, version 6.0
  • Microsoft Macro Assembler for OS/2, version 6.0

SYMPTOMS

With the Microsoft Macro Assembler (MASM) 6.0, the following error is generated incorrectly for instructions using the operand [ebx][ebx]: 

   error A2029 : multiple base registers not allowed
For example: 

   lea esi, [ebx][ebx]
   mov esi, [ebx][ebx]

RESOLUTION

A workaround for this problem is to embed the opcode for the instruction directly in the code. The sample code below demonstrates this method.

STATUS

Microsoft has confirmed this to be a problem in MASM version 6.0. This problem has been corrected in MASM version 6.0a.

MORE INFORMATION

Error A2029 will be incorrectly generated for the following program. The code that should be generated for lea esi [ebx][ebx] is 8D 34 1B. Note that the operand [ebx][ebx] is available only when using the .386 or .486 directives.

Sample Code

; Assembler options needed none

.386 .MODEL flat .STACK 4096

CODE32 SEGMENT PUBLIC USE32 

 main PROC near
    lea esi, [ebx][ebx]      ; Replace this by BYTE 8Dh, 34h, 1Bh
    ret
main ENDP CODE32 ENDS

END

Additional reference words: 6.00 buglist6.00 fixlist6.00a
KBCategory: kbtool kbfixlist kbbuglist
KBSubCategory: MLIss
Solution Type : kbfix

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Last reviewed: September 16, 1997
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